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This invention relates in general to hub assemblies, and more particularly to a process for capturing a bearing race on a spindle by deforming the spindle behind the race.
Most automobiles of current manufacturing, and many sport utility vehicles as well, have their front and rear wheels independently suspended. Typically, on such a vehicle, each road wheel is attached to a suspension system component, such as a steering knuckle, through a hub assembly, which more often than not is supplied to the automobile manufacturer as a packaged unit. Basically, such a unit includes a housing which is bolted to the suspension system component, a hub to which the road wheel is bolted along with a brake disk or drum, and an antifriction bearing which is located between the hub and the housing to enable the hub to rotate in the housing with minimal friction. The hub has a flange against which the wheel is fastened and a spindle which projects from the hub into the housing. The bearing includes outer and inner raceways carried by the housing and the hub spindle, respectively, and rolling elements, such as tapered rollers or balls, arranged in two rows between the outer and inner raceways, with the raceways being oriented to enable all of the rolling elements to transfer radial loads and the rolling elements of the one row to take thrust loads in one direction and the rolling elements of the other row to take thrust loads in the other direction. In order to assemble such a unit, at least one of the raceways must reside on a race that is initially separate from the housing or hub spindle which carries the raceway. Typically, it is the inboard inner race that is carried by the spindle. It usually resides on a cone, where the bearing is a tapered roller bearing, or a ring, where the bearing is an angular contact ball bearing. This inner race requires some type of abutment to retain it on the spindle.
One procedure for providing the abutment to retain the initially separate inner race involves upsetting the end of the spindle after the inner race is installed over the spindle. Initially, the spindle extends beyond the inner race. Then the extended portion of the spindle is deformed outwardly and backwardly against the inner race to provide a formed end which captures the inner race on the spindle. International application PCT/GB98/01823, published under International Publication No. WO98/58762, discloses a procedure and machine for upsetting the end of a hub spindle.
However, if the end of the spindle is deformed too forcefully against the inner race, the inner race may actually deform and detract from the operation of the bearing. On the other hand, the end of the spindle may not deform to the extent required to maintain a desired setting in the bearing, usually preload. In this event, a gap will usually exist between the initially separate inner race and the deformed end, in which event the bearing may operate with excessive end play. That reduces the size of the load zone in the bearing, in that it concentrates the radial load in relatively few rollers. Moreover, it leaves the spindle free to wobble in the housing which can damage the seals at the end of the bearing. Thus, the end of the spindle must be deformed with a good measure of precision.
The present invention resides in a process which upsets a deformable end on a spindle to create a formed end which captures a bearing race on the spindle. The spindle and a forming tool are forced together, with the deformable end being against the forming tool, and the force exerted is great enough to deform the end outwardly. That force is monitored during the deformation and a subsequent dwell. If the force fails to satisfy certain criteria, the hub assembly may not be satisfactory.